-----maxima-bounces at math.utexas.edu wrote: -----
>On 7/7/07, Barton Willis <willisb at unk.edu> wrote:
>
>> I think the summand in (%o1) isn't fully simplified:
>>
>> (%i44) (3^(i1+1)-2*2^i1)*x^i1;
>> (%o44) (3^(i1+1)-2^(i1+1))*x^i1 <--- the summand in (%o1) should
>> simplify to this
>>
>> The standard expand( ...,0,0) trick doesn't simplify (%o1) to
>> the (%o2). Yikes.
>
>Maybe the bug is in the summation code.
No, I don't think simpsum is guilty. Lookie here:
(%i1) powerseries((1)/((1-2*x)*(1-3*x)), x, 0);
(%o1) sum((3^(i1+1)-2*2^i1)*x^i1,i1,0,inf)
Let's extract the summand and try to simplify:
(%i2) first(args(%));
(%o2) (3^(i1+1)-2*2^i1)*x^i1
The expand(...,0,0) doesn't simpify (%o2) to (3^(i1+1)-2^(i1+1))*x^i1
(%i3) expand(%,0,0);
(%o3) (3^(i1+1)-2*2^i1)*x^i1
But
(%i4) (3^(i1+1)-2*2^i1)*x^i1;
(%o4) (3^(i1+1)-2^(i1+1))*x^i1
Barton